In recent years, an organic electrophotographic photoreceptor containing an organic photoconductive material (hereinafter, referred to also as an organic photoreceptor or to simply as a photoreceptor) has been most widely used as an electrophotographic photoreceptor. It is advantageous in the organic photoreceptor in comparison to other photoreceptors that a material suitable for various light exposure sources of visible light to infrared light is easy to be developed, a material with no environmental pollution can be selected, and manufacturing cost is low, but there is a problem such that mechanical strength is weak, the photoreceptor surface is deteriorated during printing or copying of a large number of sheets, and scratches are easy to be generated on the photoreceptor surface since durability is insufficient.
It has been strongly demanded to reduce wear caused by scraping through a cleaning blade or the like in order to improve durability of the organic photoreceptor. For this reason, a technique, in which a protective layer exhibiting high strength is provided on the photoreceptor surface, has been studied. For example, it is reported that a colloidal silica-containing curable siloxane resin is used for the surface layer of the photoreceptor (Patent Document 1). The colloidal silica-containing curable siloxane resin is easy to reduce electrical resistivity of the surface layer and to generate image blur and image flow, since both the curable resin having a siloxane bond (Si—O—Si bond) and colloidal silica exhibit moisture absorption.
Further, as to a curable resin applied to a protective layer, proposed is a protective layer made of the curable resin obtained via photopolymerization with a compound having an acryloyl group or the like (Patent Document 2). Filler such as metal oxide or the like is contained in the protective layer, but bonding between the filler and the curable resin is weak, strength for the protective layer is insufficient, and the problems such as image blur and image flow have not yet been solved sufficiently.